Fast-Growing Chickens: Welfare Concerns & Meat Quality

Broiler chickens — chickens raised for meat — undergo extreme genetic selection by farming operations. These birds are selected with the goal of maximizing productivity, defined by producers in economic terms like growth rate and volume of breast meat. Most broiler chickens raised today are “fast-growing” genetic strains that reach their “target weight” in as few as 5-7 weeks from birth.

However, research has shown that these fast-growing genetic strains, favored by producers for their efficiency, can have very poor welfare. These chickens often suffer from cardiopulmonary problems, are less active, and have limited mobility as their body weight grows faster than their leg strength. For their part, producers are increasingly concerned that fast-growing strains also produce lower quality meat.

In this study, researchers at the University of Guelph wanted to actually measure these outcomes by monitoring over 7,500 broiler chickens with different growth rates over the course of two years. The researchers collected detailed information about their behavior, mobility, anatomy, and physiology to understand how growth rate affected health and welfare outcomes. To better understand how welfare concerns aligned with commercial incentives, they also collected information on feed efficiency (the amount of feed required for the chicken to gain one pound) and meat quality. Compared to previous research, this study used a much larger sample and more carefully-controlled external factors, making it a highly comprehensive look at the relationship between growth rate, bird welfare, and production metrics.

Researchers placed each experimental group of birds in a pen featuring enrichments like a perching area, peckstone, rope, and hanging scale. Some birds were outfitted with a wearable device — a kind of fitbit for chickens — that recorded the birds’ activity, and researchers recorded the time birds spent standing, walking, and using the pen’s enrichments. Occasional “obstacle courses” were constructed for the birds, allowing researchers to assess whether the birds were capable of sustained activity to obtain food or water, or to avoid unpleasant experiences.

The study found that slower-growing genetic strains had better welfare outcomes across almost every metric tested. The slower-growing birds were the most active, spending almost twice as much time standing and walking as conventional strains did. They had fewer potentially painful footpad lesion sores than conventional strains did. And their greater use of pen enrichments suggested a greater capacity for motivated activity, a key measure of welfare.

Conversely, conventional fast-growing birds showed lower activity levels and had difficulty completing the obstacle courses. When faced with standing for ten minutes or having to sit in a puddle of water (an unpleasant experience for the birds), conventional genetic strains were able to stand for a much shorter amount of time. This suggests that faster-growing birds’ body weight increases faster than their leg strength, leaving them unable to support their weight.

Some production metrics measured in the study confirmed the advantages of fast-growing broiler strains for farming operations: they produced more meat and required less feed and resources over their lifetime than slower-growing strains. But these fast-growing strains also had some significant downsides for producers. Compared to slower-growing birds, fast-growing strains had a much higher prevalence of wooden breast and white striping, muscle disorders that can reduce meat quality. These muscle disorders have a notable financial impact on producers because they significantly reduce the price producers can obtain for meat.

Producers have moved quickly to improve welfare standards when it is aligned with market pressures. Recent research has shown that after learning more about welfare concerns, many consumers are willing to pay more for meat with higher welfare standards. This study provides more evidence that slower-growing broiler strains not only enjoy higher welfare, they also produce higher quality meat. For animal advocates, these results suggest that, especially as consumer concerns about welfare increase, the use of slower-growing broilers might improve both bird welfare and producers’ bottom lines.